Who Qualifies for Medicare, and When Should You Sign Up?

Short answer: You qualify for Medicare at 65 if you're a U.S. citizen, or a lawful permanent resident who has lived in the U.S. for 5 continuous years. You can qualify earlier after 24 months of Social Security disability benefits, as soon as disability benefits start if you have ALS, or if you have end-stage renal disease. Most people should sign up during the 7-month window around their 65th birthday to avoid gaps and lifelong penalties.

Medicare enrollment is one of the few retirement deadlines with a permanent price tag for missing it. This guide explains who is eligible, when to sign up, and how the timing fits with Social Security, a job you might keep past 65, and your retirement budget.

FinancialAdviser.com is not connected with or endorsed by the U.S. government or the federal Medicare program, and we don't sell Medicare plans. This guide is general education, not advice about your coverage.

Who Qualifies for Medicare?

According to the Centers for Medicare & Medicaid Services (CMS), these groups can get Medicare Part A (hospital insurance) and Part B (medical insurance):

Who	When Medicare can start
People 65 and older	The month you turn 65, if you sign up before that month. U.S. citizens, or lawful permanent residents with 5 continuous years in the U.S., can buy Part A (if not premium-free) and Part B.
People getting Social Security or Railroad Retirement Board disability benefits	Part A automatically after 24 months of disability benefits
People with ALS (Lou Gehrig's disease)	The first month you're entitled to disability benefits, with no 24-month wait
People with end-stage renal disease (ESRD)	Generally the third month after regular dialysis begins, or the month of a kidney transplant, if you apply and meet work or benefit conditions
Disabled government employees not eligible for Social Security or RRB disability benefits	Part A after 29 months

You don't need to have retired to qualify. The age for Medicare eligibility is still 65, even though Social Security's full retirement age is later for most people retiring today. That gap is where many enrollment mistakes start: some people assume Medicare waits until they claim Social Security. It doesn't. Our guide on when to claim Social Security explains how full retirement age works.

Is Medicare Part A Free?

For most people, yes. Premium-free Part A depends on work history, not age alone. CMS says about 99% of Medicare beneficiaries don't pay a Part A premium because they have at least 40 quarters of Medicare-covered employment, as determined by the Social Security Administration.

If you have fewer quarters, you can still buy Part A. The 2026 monthly Part A premiums are:

Quarters of Medicare-covered work	2026 Part A premium
40 or more	$0
30 to 39	$311 a month
Fewer than 30	$565 a month

Part B isn't free for anyone paying the standard rate. In 2026, the standard Part B premium is $202.90 a month and the annual Part B deductible is $283, according to CMS. The Part A deductible for an inpatient hospital stay is $1,736 in 2026. Build these into your retirement budget alongside whatever drug and supplemental coverage you choose.

When Can You Sign Up for Medicare?

There are three main enrollment windows. Medicare.gov and the Social Security Administration describe them this way:

1. Initial Enrollment Period (IEP). Seven months long: it starts 3 months before the month you turn 65, includes your birthday month, and ends 3 months after. There's no penalty for signing up in this window.
2. Special Enrollment Period (SEP). If you or your spouse are still working and covered by that employer's group health plan, you can sign up any time while covered, or within 8 months after the job or the group coverage ends, whichever comes first. There's no penalty if you use it.
3. General Enrollment Period (GEP). If you missed the other windows, you can sign up from January 1 through March 31 each year. Coverage starts the month after you sign up, and a late enrollment penalty usually applies.

When Does Coverage Start?

Timing inside your Initial Enrollment Period matters. Medicare.gov gives these Part B start dates:

If you sign up	Part B coverage starts
In the 3 months before the month you turn 65	The month you turn 65
In the month you turn 65 or the 3 months after	The month after you sign up

Premium-free Part A starts the month you turn 65. If your birthday is on the first of the month, coverage starts the month before. Coverage always begins on the first day of a month.

The retirement-planning takeaway: if your current health coverage ends when you turn 65 or retire, signing up before your birthday month is the simplest way to avoid a gap. Medicare.gov also suggests that if you're leaving a job with health coverage, you sign up for Part B the month before you plan to retire so Medicare starts when the job-based coverage ends.

Do You Get Medicare Automatically?

Sometimes. If you've been getting Social Security or Railroad Retirement Board benefits for at least 4 months before you turn 65, you're enrolled in Part A and Part B automatically. Medicare mails your card about 3 months before coverage starts. You can decline Part B if you have other qualifying coverage, such as an active employer plan.

If you haven't started Social Security, which is common for people waiting until full retirement age or 70 to claim larger benefits, you have to sign up for Medicare yourself. You can apply through Social Security without starting your retirement benefits. Use our Social Security age calculator to see how claiming age changes your benefit, but don't let that decision delay your Medicare sign-up.

What Are the Medicare Late Enrollment Penalties?

Penalties are added to your monthly premium, not charged once. Medicare.gov lists three:

• Part B: 10% for each full 12-month period you could have had Part B but didn't. It usually lasts as long as you have Part B, which for most people means the rest of their life. Using 2026 figures, someone who waited 24 months pays a 20% penalty, or $40.58 on top of the $202.90 standard premium, for a total of $243.50 a month after rounding.
• Part A: If you have to buy Part A and don't sign up when first eligible, the premium may rise 10%, for twice the number of years you went without it.
• Part D (drug coverage): 1% of the national base beneficiary premium for each month you went without creditable drug coverage after first becoming eligible, or after a gap of 63 days or more. In 2026, the base premium is $38.99, so a 14-month gap means a 14% penalty of about $5.50 a month. It lasts as long as you have Medicare drug coverage.

You generally avoid these penalties if you qualify for a Special Enrollment Period, have creditable drug coverage, or qualify for programs such as Extra Help or a Medicare Savings Program.

Should You Delay Medicare if You Work Past 65?

It depends on the coverage you have. The Special Enrollment Period only protects you if the coverage is a group health plan based on current employment, yours or your spouse's. A few rules to know:

• COBRA and retiree health coverage don't count. The 8-month window starts when the job ends, even if you elect COBRA. Waiting for COBRA to run out can leave you with a penalty.
• Small employers have their own rule. If your employer has fewer than 20 employees, Medicare.gov says you can sign up any time while you're still working there, or within 8 months after the work or the coverage ends, whichever comes first. Check with the plan about how it works with Medicare.
• Watch your health savings account. Social Security warns that contributing to an HSA after Medicare coverage begins may result in additional taxes. Because Part A can be backdated up to 6 months when you sign up after 65, plan when to stop HSA contributions before you apply.
• Marketplace coverage ends its subsidy. Medicare.gov says that once you're eligible for Part A, you lose Marketplace premium help, so plan to end that coverage when Medicare begins.

Where Can You Get Free Help?

For questions about your own situation, use official, unbiased sources:

• Medicare: Medicare.gov or 1-800-MEDICARE (1-800-633-4227).
• Social Security: For enrollment, eligibility and premium-free Part A questions.
• Your State Health Insurance Assistance Program (SHIP): Free, unbiased one-on-one counseling about Medicare choices.

The Bottom Line

Most people qualify for Medicare at 65, and some qualify earlier through disability, ALS or ESRD. Mark your 7-month Initial Enrollment Period on the calendar, sign up before your birthday month if you'll need coverage right away, and only delay Part B if you have job-based group coverage from current work. Then build the Part B premium and deductible into your retirement budget. For more on the rest of retirement planning, see our retirement guides.

Frequently asked questions

Who qualifies for Medicare?

People 65 or older who meet citizenship or residency rules, people under 65 who have received Social Security or Railroad Retirement Board disability benefits for 24 months, people with ALS once their disability benefits start, and people with end-stage renal disease who need regular dialysis or have had a kidney transplant and meet work or benefit conditions.

Do I have to sign up for Medicare at 65 if I'm still working?

Not always. If you or your spouse are still working and covered by that employer's group health plan, you can usually sign up for Part B later during a Special Enrollment Period without a penalty. That window lasts up to 8 months after the job or the coverage ends, whichever comes first. COBRA and retiree coverage don't count as coverage based on current work.

Do I get Medicare automatically?

If you've been getting Social Security or Railroad Retirement Board benefits for at least 4 months before you turn 65, you're enrolled in Part A and Part B automatically, and your card arrives about 3 months before coverage starts. If you haven't started Social Security, you need to sign up.

Is Medicare Part A free?

For most people, yes. CMS says about 99% of beneficiaries don't pay a Part A premium because they or a spouse have at least 40 quarters of Medicare-covered work. In 2026, people with 30 to 39 quarters pay $311 a month and people with fewer than 30 quarters pay $565 a month.

What happens if I miss my Initial Enrollment Period?

You can sign up during the General Enrollment Period, January 1 through March 31 each year, with coverage starting the month after you sign up. You may owe a late enrollment penalty for as long as you have Part B unless you qualify for a Special Enrollment Period.

Sources

1. CMS: Original Medicare (Part A and B) Eligibility and Enrollment
2. Medicare.gov: When Does Medicare Coverage Start?
3. Medicare.gov: Avoid Late Enrollment Penalties
4. Social Security Administration: When to Sign Up for Medicare
5. CMS: 2026 Medicare Parts A & B Premiums and Deductibles

This guide is general information, not personal advice. Your situation may differ, so consider talking with a qualified professional, such as a fiduciary financial adviser, CPA or licensed agent, before making a decision.